Known headlight units include a reflector and a lamp mounted within a lamp mounting cavity. In operation, light is emitted from the lamp and reflected at the reflector to form a beam of desired illumination properties, in particular for front lighting of a motor vehicle.
In operation, electrical power supplied to the lamp is only partially converted into light, whereas the remaining portion heats up the lamp. Known incandescent lamps have a relatively low efficiency, so that an increased amount of heat is generated. However, incandescent lamps, in particular halogen lamps, can generally withstand higher temperatures. Also, in incandescent lamps, heat generated in the filament is efficiently radiated to the outside.
LED lamps have a higher efficiency, but are more sensitive to temperature. Heat is generated in a comparatively small space, and is not efficiently radiated. Thus, in particular for headlight units with LED lamps, thermal management is important.
JP 2013030371A describes a headlamp for a motor vehicle. The headlamp comprises an LED and a driver circuit which are directly attached to a heat radiating portion. The driver circuit is sealed by a resin. The heat radiating portion comprises a front surface, an extension portion extending up to the LED, and a radiation fin formed in a rear surface.
DE 10224004 A1 discloses a headlight unit comprising a reflector and a lamp. The lamp comprises a driver and a heat sink 12 mounted at the driver. The lamp is mounted in a cavity of the reflector. The cavity is sealed by a flexible cap.